Just joined after I saw the postings on the Moscode 300. I found one, unmodified, two years ago and have been using it ever since. Couple of observations: resistors R34,36,37, and 39 run very, very hot. I replaced them with 5-10 watt ratings and they still run very hot. Can't imagine the original resistors are still functional. Is George Kaye still around? He never responded to my emails one-two years ago. Whatever. The power switch is unreliable, replace it if you can. I used one from a retired Hafler 220, works fine.If anyone is thinking of upgrading any components, I had a hard time finding CS1, a CR300 current regulator (obsolete now), found them on Ebay. Also C15, the 330V 880 mic capacitor is hard to find, but George Kaye himself said somewhere in DIY Audio that one can "use anything that fits that's over 100 mic." The amp is a blast, powers my homemade Jazzman Mark 5 ESLs. Love it.